Core C: Abstract The overarching theme of program is to dissect a new concept that in Acute Respiratory Distress Syndrome (ARDS), immunosuppression is a signature manifestation secondary to unique, combinatorial pathways that modulate epithelial and myeloid cell viability and innate immune function. We focus on pneumonia as a conceptual framework to study immunosuppression, as pneumonia is a common cause and risk factor for ARDS. The faculty within the Imaging Core have been collaborating continuously and productively with the PI?s of this program for 23 years in various aspects of immunobiology, lipid biology andairway/pulmonary biology resulting in 37 collaborative papers. The principal roles of the imaging core will be; careful analysis of cellular and molecular processes associated with apoptosis, necrosis, ferroptosis and other cell death mechanisms as needed, characterization and quantification of cell types within tissues, examination of protein expression during cell death, examination of cell-cell interactions in vitro, quantitative analysis of cellular migration in vivo and ex vivo individual cells within tissues, and quantitative measurement of the levels and patterns of expression of chemokines and cell-type markers various samples at all levels of resolution. These studies will employ the full array of current light, and potentially, electron microscopic methods including: single and multicolor fluorescence microscopy, laser confocal microscopy live cell imaging, transmission electron microscopy and computer-aided morphometric analyses . The Center for Biologic Imaging, in which this core service will be performed, is designed for the purpose of providing state of the art microscopic technologies to its users. It is equipped to perform a continuum of optical methods including all types of light and electron microscopy essential to this Program Project.